Berlin: Arjen Robben is relishing Bayern Munich's forthcoming "week of truth" when they host Arsenal in the Champions League with the German champions currently struggling for form.

Bayern scraped into the quarter-finals of the German Cup on Tuesday with a 1-0 win at home to Wolfsburg, thanks to Douglas Costa's first-half goal and heroics from Germany goalkeeper Manuel Neuer.

Arjen Robben eyes success against Arsenal. Reuters

The Germans are bidding to reach the Champions League's semi-finals for a sixth season in a row.

They host Arsenal on Wednesday on the back of a record 15-game winning streak in European matches at the Allianz Arena.

Carlo Ancelotti's star-studded Bayern are four points clear in Germany's top flight and are at relegation-threatened Ingolstadt away on Saturday in the Bundesliga.

Robben says Bayern need a good performance at their Bavarian neighbours in their final fine-tuning before hosting the Gunners in the first-leg tie of the Champions League's last 16 round with the return in London on 7 March.

The Dutchman scored against the Gunners in November 2015 when Bayern battered Arsenal 5-1 at the Allianz Arena, but is taking nothing for granted.

"Our performances haven't been good enough and we have to do a few things better," said Robben.

"We have to talk about this in training and make sure we play as a team."

"Arsenal will be 'the week of truth' and will be exciting.

"Normally, we are always where we need to be for games like that, but it is a completely different game.

"It'll be a step up.

"It's Champions League and the opponents are always better."

Bayern were far from impressive in sealing 2-1 wins at both Freiburg and Werder Bremen in their opening two league games of 2017.

Ancelotti has said the defence must improve, highlighting the big gap between his back four and the midfield in Saturday's 1-1 draw against Schalke.